A company like CNET will use its own web designers and they will use any number of different tools to design these web sites. They could even use a simple text editor like Notepad to design the web site.
The buttons, effects, borders, shading, input boxes, etc all come down to experience and knowledge of web page design.
To show you what I mean, with any CNET web site open, goto View > View source, and see the coding they have used to design the page you are looking at. Although they could be using something like Dreamweaver, that coding could as easily be done in Notepad.
What software did cnet use to create their site? What is the best one that uses very nice interfaces (buttons, taskbars.etc)like cnets?